jpa注解

系统生成uuid注解配置：

@Id

@GenericGenerator(name ="system-uuid", strategy ="uuid2")

@GeneratedValue(generator ="system-uuid")

@Column(name ="id",length =64)

一对多不产生外键关联关系，重点是foreignKey ：

@OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY)

@JoinColumn(name ="project_application_id", foreignKey =@ForeignKey(name ="none", value = ConstraintMode.NO_CONSTRAINT))

非外键关联配置，重点是referencedColumnName 指向关联表的字段：

@ManyToOne(fetch = FetchType.LAZY)

@JoinColumn(name ="service_coupons_type", referencedColumnName ="service_coupons_type", foreignKey =@ForeignKey(name ="none", value = ConstraintMode.NO_CONSTRAINT))